Mechanism for and method of rifling gun barrels



- June 28,1938. SIMPSON 2,121,832

MECHANISM FOR AND METHOD .OF RIFLING GUN BARRELS Filed Feb. 24, 1937 s Sheets-Sheet 1 t /2 6 H ,65 I

- Inventor Clarence E -Simpsun June 28, 1938. c. E. SIMPSON 2,121,832

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MECHANISM FOR AND' METHOD OF RIFLING GUN BARRELS Filed Feb. 24, 1937 s Sheets-Sheet s lnv eritu'r" filarencefijimpsun' Atturney Patented June 28, 1938 UNITED STATES PATENT OFFICE,-

MECHANISM FOR AND METHOD OF BIFLING GUN BARRELS Clarence E. Simpson, Springfield, Mass. Application February 24, 1937, Serial No. 12'l,506

6 Claims. (01. 90-281) (Granted under, the act of March .3, 1883, as

' amended April 30, 1928; 370 0.'G. 757) The inventiondescribed herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon. The subject of this invention is a mechanism for and method of riding gun barrels, and relates more particularly to a means for and method of rifling a gun barrel having an irregular bore when finished.

The main objects of the invention are the provision of a method of forming a rifled barrel having a varying diameter of bore, and of means for rifling-such a barrel.

The invention is carried out broadly by rifllng 16 the barrel to varying depths and then reaming out the bore to the desired form, specifically it is accomplished by utilizing a specially constructed rifling bar to rifle the barrel to the varying depths desired and then reamingout the bore to 20 the desired shape.

A practical embodiment of a machine'for rifllng a barrel is shown by way of illustration in the accompanying drawings'wherein:

Fig. 1 is an elevation showing the left side of 25 a Pratt and Whitney Company rifling machine with the rifiing mechanism forming the subject of this invention installed thereon,

Fig. 2 is a plan view of the carriage and riding mechanism, 30 Figs. 3 and 3a. are longitudinal sectional views of the carriage and rifllng mechanism,

Fig. 4 is an enlarged sectional View of the ,rifiin'g bar, a Fig. 5 is a cross section on the line 5-5 of 85 Fig. 3.

Fig. 6 is a cross section 'on the line 6-6 of Fig. 3,

Fig. 7 is a cross section on the line 1-1 of Fig. 3. v -Fig. 8 is across section on the line 8-8 of Fig. 3. p

Fig. 9 is a longitudinal sectional view of the expansion screw nut, I

Fig. 10 is an end view. of the'expansion screw nut,

Fig. 12-is a view inelevation, partly in section 50 of the expansion cam,

Fig.113 is a view in end elevati pansion cam,.

; Fig. '14 is a plan view of the index slide plate, Fig.',15 is a view in side elevation of the plate,

55 Fig. -16 is a plan view ofthe rifling cutter,

, .Fig. 11 is a plan view of the expansion screw on of the ex- Fig. 17 is a view in side elevation of the rifling cutter,

Fig. 18 is an end viewof the rifllng cutter,

Fig. 19 is an end view of the rifiing rod holder,

Fig. 20 is a plan view of the adjusting screw I lock,

Fig. 21 is an end elevation of the adjusting screwlock.

Referring to the drawings by numerals of reference: i

There is provided a rifllng machine, preferably the Pratt and Whitney Rifling Machine No. 3, which has a carriage l reciprocated in the usual manner by a lead screw, not shown, and carrying a transverse guide 2 in which slides a rack'3 reciprocated in the guide through means of a stud, not shown, sliding in the groove-of cam bar 4. The foregoing is standard equipment and forms no part of the present invention. a

Mounted on the carriage l is a bearing 5 carrear of the bearing 5 is an expansion cam 8 held 25 in place by a retaining ring 9 which is .threaded into' the cam housing I.

Extending through the bearing 5 and into the expansion cam housing I is the. enlarged portion of a hollow shaft l0 bifurcated for a short distance at its rear end as indicated by the numeral I l. The forward reduced end of this shaft l0 enters a bearing l2 carried in a bearing block 13 spaced from the bearing block 6. Mounted on the shaft i0 between the blocks 6 and I3 are pinions I 4 and li'suitably keyed to the shaft as at I 6l6, and also mounted on the shaft is an adjusting collar H which may be locked in ad- .iusted position by the set screw I8, the purpose of the collar being to retain the pinions in proper 40 position with relation to each other.

Within the enlarged rear portion of the shaft I0 is positioned an expansion screw nut IS in the form of a tubular member interiorly threaded adjacent to its rear end and formed at that end with diametrically opposite wings 20-20 adapted Y the expansion screwnut l9 so as to permit the nut a motion of translation with respect to the shaft. The pin 2| also passes through an aperture in a seat block 22 which is located within the expansion screw nutl9 and forms an abutment for the rear end of a cutter collapsing spring 23, the forward end of which engages the expansion screw plug 24 threaded into the forward end of the expansion screw nut l9 and apertured to receive the cutter rod 25 which may be locked in place therein as by the screw- 26. A thrust washer 21 is preferably positioned between the rear end of the expansion cam housing 'I and the expansion cam 8 to take the thrust of plungers 28 mounted in recesses in the cam and acted on by springs 29.

Threaded into the rear end of the expansion cam housing 7 is an expansion screw nut stop 30 axially bored to permit the passage of an expansion screw 3|. The stop may be locked in place by a set screw 32. The expansion screw extends rearwardly into its housing 33 which is carried in a block'34 formed on the carriage. The housing 33 is keyed in the block to permit limited sliding movement thereof with relation to the block. The expansion screw 3| is headed at its rear end, and between the head and forward wall of the housing is a spring 35 surrounding the screw shank. A key 36 is carried by the head and enters a keyway 31 formed in the housing. The rear end of the housing 33 is serrated as at 38 to receive a lock 39 of the adjusting screw 40.

The lock 39 is preferably a finger extending radially from a tubular member 41 within which is a lock screw 42 threaded into the adjusting screw 4B and serving to confine between its head and the bottom of the tubular member 4| a spring 43 which urges the look toward its forward or serration engaging position. The adjusting screw is formed at its rear end with a knob 44 and is slotted at 45 to accommodate the lock.

Between the rear end of the expansion cam housing I and the block 34 is positioned a collapsible dog 46 mounted on the forward end of a shaft 41 which is journaled in the block 34 and has squared on its rear end a lever 48. A lip 49 on the lever may engage under the head of a screw 50 for the purpose of retaining the assembly in place. The dog 46 is dished out on its rear face at 5| to be engaged by the beveled forward edge 52" of the expansion screw housing 33 to thereby cam the dog 46 to one side.

Within the bearing I2 is positioned with a turn. ing fit the rear end of a sleeve 53 to which the forward end of the hollow shaft I6 is keyed as at 54. The forward end of the sleeve is slotted to receive the wings 55-55 projecting from the rifiing rod holder 56, the rear end of which enters the front end of the sleeve with a close fit and which is clamped in place by a cap nut 57 threadved .on-the front end of the sleeve and locked by a nut 58 threaded on the rifiing rod holder '56. A wire or cable-59 has its rear end secured in the cutter bar 25 and passes through the rifiing rod holder 56 and rifiing rod 60 and has its front end secured to a cutter expanding wedge 6| which operates to position the rifiing cutter 62 to the proper depth of cut.

The gun barrel is bored in the usual way to the desired caliber, it is then rifled to the .desired depths with the device herein shown or in other a manner, and the lands then reamed to give the interior of the barrel the desired contour.

The operation of the rifiing device herein shown is as follows:

When a cutting stroke is started the expansion the pull of the cutter will be sufficient to cause the expansion screw housing to slide forwardlyin its bearing until its forward beveled edge 52 meets the cam surface 5| of the collapsible dog 46. This movement is due to the expansion screw 3| moving into the expansion nut as the rifiing bar is rotated.

After the forward end of the housing contacts the collapsible dog, the resistance will be sufficientto cause the expansion screw 3| to be held stationary until the cutter collapsing spring 23 has been compressed by the rearward travel of the expansion screw nut l9 until it contacts its stop 30. During this portion of the action, the rifiing cutter 62 will be gradually wedged outwardly to a greater depth of cut.

During the remainder of the cut,,the spring 35 will be com-pressed until the key 36 reaches the 5 end of the keyway 3'! when the dog 46 will be collapsed and the springs will cause the rifiing cutter 62 to be retracted for the return stroke.

The depth of cutis regulated by turning the expansion cam housing I through means of the ratchet teeth 63 formed thereon and acted upon by the index slide 64 to rotate the casing with a step by step movement.

I claim:

1. The combination with a rifiing machine including a carriage and means for axially rotating a rifiing bar, of a rifiing bar, a cutter carried by the rifiing bar, and mechanism actuated by the bar rotating means to automatically expand the cutter a predetermined amount upon starting a cutting stroke; retain the cutter in such position duringadesired portion of such stroke; gradually expand the cutter during another portion of the stroke; and maintain a uniform depth of cut during the remainder of said stroke.

2. The combination of a rifiing machine including a carriage and means for axially rotating a rifiing bar, of a rifiing bar, a cutter carried by the bar, a wedge for expanding the cutter, and mechanism actuated by the bar rotating means to automatically move the wedge to expand the cutter upon start of a cutting stroke;

retain the wedge in such position during a predetermined portion of such stroke; gradually move the wedge to further expand the cutter during a, subsequent portion of such stroke; and

then retain thewedge' in such final position durby the rifiing bar, and mechanism actuated by the'bar rotating means to automatically expand v the cutter at the start of a cutting stroke; retain the cutter in such expanded position during a predetermined portion of such stroke: further expand the cutter during a subsequent portion of such stroke; retain the cutter in expanded position during the remainder of thestroke; and collapse the cutter upon completion of the stroke.

4. The combination with a rifiing machine including a carriage and means for rotating a rifiing bar, of a rifiing bar, a cutter carried by the rifiing bar, and mechanism actuated by the bar rotating means for expanding the cutter at the start of a cutting stroke; further expanding the cutter during such stroke; and automatically retracting the cutter at the end of the stroke.

5. The combination with a rifling machine including a. carriage and means for rotating a rifling bar, of a rifling bar, a cutter carried by the rifiing bar, and mechanism actuated by the bar rotating meansfor varying the depth of cut of the cutter during a cutting stroke and retracting the cutter at the end of the cutting stroke.

translate the nut axially, a connection between the nut and cutter, an expansion screw engaged by the nut, means associated with the nut and means associated with the screw cooperating upon rotation of the bar during a cutting stroke whereby the screw advances into the nut durin a predetermined portion of the stroke; the nut gradually threads on the screw during a. further and means for rotating the bar.

CLARENCE E; SIMPSON. 

